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Currently, the development of energy production projects in the building sector using alternative energy sources such as solar energy is growing rapidly. This increasing technological progress to achieve the needs of comfort and safety can be considered a major priority, particularly with concerns about energy shortages and current environmental issues threatening not only human well-being but ecosystems as well. The present research aims to provide a comprehensive model for enhancing the energetic performance of rural Moroccan houses, by exploring solar radiant heating systems. The evaluation of the solar floor heating system is carried out by trnsys to evidence the effect of various design parameters on performance indexes of the system concerning six Moroccan cities, which representatively correspond to the Moroccan climatic zoning. The examined analyses cover the effect of the collector area, storage tank volume, and mass flowrate in the solar loop and the building heating loop. Moreover, how the variation of thickness and piping material affect the performances was discussed as well. The major finding of this work is optimizing the system performance gives the possibility to meet adequately the heating load. The energetic analysis shows the system's adaptability to the Moroccan climate, whose solar fraction is around 65% and 87%. For most of the examined sites, it was observed that the demand for auxiliary energy is limited from October to May. The economic investigations revealed that payback periods of the examined system ranged between 7 and 13 years. Besides, the energy and economic outcomes of such systems in Morocco, they are capable to mitigate the huge amount of CO2 emissions as compared to conventional heating systems.

Investigation of band structure and thermo-physical response of the d0 new quaternary Heusler compounds KSrCZ (Z = P, As, Sb) within the frame work of density functional theory with full potential linearized augmented plane wave method has been analyzed. Results showed that type-Y3 is the most favorable atomic arrangement. All the compounds are found to be half-metallic ferromagnetic materials with an integer magnetic moment of 2.00 μB and a half-metallic gap EHM of 0.292, 0.234, and 0.351 eV, respectively. The half-metallicity of KSrCZ (Z = P, As, Sb) compounds can be kept in a quite large hydrostatic strain. Thermoelectric properties of the KSrCZ (Z = P, As, Sb) materials are additionally computed over an extensive variety of temperature and it is discovered that all compounds demonstrates higher figure of merit. The properties of half-metallicity and higher Seebeck coefficient makes these materials a promising candidates for thermoelectric and spintronic device applications.

In order to develop a mathematical modeling of the smart structure, the study consists of using, in first time, the finite element method and Euler-Bernoulli theory applied to a flexible beam divid...

Nowadays, optically smart thin materials are becoming more attractive to researchers in the field of building energy efficiency. This is due to their capacity to regulate radiative heat transfer through the dynamic variability of their optical properties depending on an external stimulus (natural or human). In this chapter, the categories of optically smart thin materials such as thermochromic and electrochromic coatings are presented, including all the mechanisms to manage their optical smartness. Classical and new methods used to fabricate these materials are detailed. Their applications of those materials as smart thermal building insulators and their impact on cooling and heating energy consumption are discussed.

Global climate change initiatives have recommended significant changes in mobility technologies due to increasing emissions in the transportation sector, which accounts for about a quarter of total global emissions. These initiatives have encouraged the use of alternative options with cleaner fuels, such as electric mobility, which is one of the most important options being introduced worldwide. Moreover, Morocco made progress toward achieving the principle of sustainability, which requires addressing many challenges, including climate protection, pollution prevention, and the preservation of ecosystems and human health, and ensured the fulfillment of Morocco's energy commitments, particularly with respect to the reliability of energy supply in the transport sector. However, electric mobility faces significant constraints to large-scale implementation, such as costs, infrastructure, and institutional barriers, which are beyond the ability of transport sector actors to overcome them. In this article, the effects of the transition to electric mobility in Morocco are analyzed using an approach called the A3 report, to address the transition towards sustainable mobility in Morocco. This analysis is supported by a research report on the evaluation of sustainable mobility in Morocco, carried out by the Moroccan Energy Federation, the Sunergia group, and Nevolys consulting.

The objective of this study is to analyze the situation of road transport in Morocco in terms of energy use. In this respect, the use of an approach that can solve some problems, such as the DMAIC approach for identifying the different sources of inefficiency and proposing recommendations to reduce them, was discussed. This approach is structured around five phases: define, measure, analyze, innovate and control. To ensure the effective use of this approach, there are many quality assessment tools such as the 5W's & H method, the Ishikawa diagram, etc.

Improving thermal insulation of buildings envelopes can reduce their energy consumption and related CO2 emissions considerably. Searching for new and innovative insulation materials is therefore a key challenge. This paper presents an experimental study to show the effect of adding spent coffee grounds (SCGs) on thermal properties of plaster composite. The obtained results using the box method show a significant decrease of thermal conductivity along with an increase of the coffee ground content, indicating the possible usage of the resulting material as efficient insulation in buildings. It is found that the thermal conductivity of the resulting building material can be decreased from 0.5 to 0.31 W/m.K by adding 6 wt% of CGs to the initial material. To illustrate energetically and environmentally the benefit of using the proposed material, annual simulations were carried out for a typical Moroccan house located in Marrakech. The results indicated that up to 20% of the cooling and heating loads of the building can be reduced if the proposed material substitutes the conventional one. From an environmental point of view, the utilization of the proposed material can reduce up to 1500 kg CO2, annually for the studied case.

Recently, solar energy is considered as the most promising renewable energy source, due to the availability and advancement of the solar technologies. This paper presents an extensive energy, economic and environmental analysis of 2.04 kWp of polycrystalline (p-Si), 2.04 kWp of monocrystalline (m-Si) and 1.86 kWp of amorphous on microcrystalline (a-Si/μc-Si) identical PV systems installed on the rooftop of 20 different institutional buildings, located in various Moroccan sites. Based on the analysis conducted, annual results are predicted with respect to hourly meteorological data and performance characteristics of each technology are examined using energetic, economic and environmental indexes (3E analysis). Daily simulation results were compared with actual recorded data for one of the geographical site (Meknes city) and good matching between simulated and recorded data has been achieved to prove its validity. The energetic analysis has shown that poly-Si modules surpassed the mono-Si and amorphous-Si modules in terms of performance, capacity factor and conversion efficiency. Besides, economic analysis has been conducted to determine the discounted payback period and levelized cost of electricity (LCOE) for 20 Moroccan cities and the results have shown that p-Si, m-Si and a-Si/μc-Si offered the 20-city average of 17.1, 21.6 and 28.6 years payback period, respectively. Moreover, LCOE has been determined for each city and the results reveal that p-Si, m-Si and a-Si/μc-Si types PV modules presented the average of 9.02, 10.13 and 12.53 cent€/kWh, respectively. Finally, the environmental analysis has revealed that average of 1.316, 1.286 and 1.051 tons of CO2 per kWp can be reduced by adopting the p-Si, m-Si and a-Si/μc-Si PV modules in the studied locations. The findings confirm the potential of the examined technologies and elucidate specific conclusions for the practice of such systems under Morocco’s climate.

This article presents a simulation model comparison between a diode and two diodes of a photovoltaic cell. The simulation model created under the Matlab-Simulink environment predicts annual performances of the three photovoltaic field technologies connected to the grid. The simulation models have been validated by the experimental data of the photovoltaic system in the meteorological conditions of the city of Meknes. The interest is to inspect the closest model that allows to obtain more reliable results in order to follow the performances and the operation of the installation in the coming years, Also to compare between the efficiency of the three photovoltaic technologies (monocrystalline, polycrystalline and amorphous) in the same climatic conditions of Meknes city in Morocco which is a Mediterranean climate with very cold winters and very hot summer.

An analytical method on the active vibration control of a functionally graded beam equipped with layers of piezoelectric sensors and actuators, in a thermal environment, is studied. The study based on Euler-Bernoulli theory and finite element method, applied to a flexible beam divided into a finite number of elements. The equations of motion are obtained by applying the principle of Hamilton. The structure is modeled analytically then numerically and the results of the simulations are presented to visualize the states of their dynamics.

Theoretical and numerical results of the modeling of a smart plate are presented for optimal active vibration control. The smart plate consists of a rectangular aluminum piezocomposite plate modeled in cantilever configuration with surface bonded thermopiezoelectric patches. The patches are symmetrically bonded on top and bottom surfaces. A generic thermopiezoelastic theory for piezocomposite plate is derived, using linear thermopiezoelastic theory and Kirchhoff assumptions. Finite element equations for the thermopiezoelastic medium are obtained by using the linear constitutive equations in Hamilton’s principle together with the finite element approximations. The structure is modelled analytically and then numerically and the results of simulations are presented in order to visualize the states of their dynamics and the state of control. The optimal control LQG-Kalman filter is applied. By using this model, the study first gives the influences of the actuator/sensor pair placement and size on the response of the smart plate. Second, the effects of thermoelastic and pyroelectric couplings on the dynamics of the structure and on the control procedure are studied and discussed. It is shown that the effectiveness of the control is not affected by the applied thermal gradient and can be applied with or without this gradient at any time of plate vibrations.

This paper aims at studying the thermal behavior of an under floor heating system via CFD calculations. The results have discussed some important parameters that need to be controlled for an appropriate operation of the system. These parameters include the velocity inside the pipes, inlet temperatures and the patterns of the tubing form. A new parameter to measure the floor thermal homogeneity has been introduced and evaluated. It is found that, generally, the modulated spiral configuration is the best configuration allowing less pressure losses and better thermal homogenization. Keywords: Under-floor heating, Design, Temperature distribution, Thermal homogenization, Configuration

This paper presents a dynamic study of sandwich functionally graded beam with piezoelectric layers that are used as sensors and actuators. This study is exploited later in the formulation of the active control laws, while using the optimal control Linear Quadratic Gaussian (LQG), accompanied by the Kalman filter. The mathematical formulation is based on Timoshenko&rsquo, s assumptions and the finite element method, which is applied to a flexible beam divided into a finite number of elements. By applying the Hamilton principle, the equations of motion are obtained. The vibration frequencies are found by solving the eigenvalue problem. The structure is analytically then numerically modeled and the results of the simulations are presented in order to visualize the states of their dynamics without and with active control.

Photovoltaic (PV) systems are the most promising renewable energy source in Morocco due to its abundant solar irradiation. The Moroccan government has launched various renewable energy programs to encourage the use of PV systems. In this work we present a comparative study in terms of energy produced and the efficiency of a grid connected photovoltaic (PV) system installed on the roof of the building occupied by the “Ecole Supérieure de Technologie de Meknes” (ESTM). The on-grid connected photovoltaic system has a total power of 5860 Watts (Wp). This system provides an average daily reduction of 30 kWh in the consumption of electrical energy at ESTM facilities; this will allow us to save fossil fuels and reduce emissions of greenhouse gas. The average annual production of electric power is estimated at 10.5 MWh, equivalent to burning 0.9 tons of oil, which will prevent the emission of about 2 tons / year of CO2 in the atmosphere. Three different commercial solar modules, manufactured with different materials and technologies in monocrystalline silicon, polycrystalline silicon and amorphous silicon were tested.

In this work, first-principles calculations of the structural, electronic and magnetic properties of Heusler alloys CoMnYAl, CoMnYGa and CoMnYIn are presented. The full potential linearized augmented plane waves (FP-LAPW) method based on the density functional theory (DFT) has been applied. The structural results showed that CoMnYZ (Z = Al, Ga, In) compounds in the stable structure of type 1+FM were true half-metallic (HM) ferromagnets. The minority (half-metallic) band gaps were found to be 0.51 (0.158), 0.59 (0.294), and 0.54 (0.195) eV for Z = Al, Ga, and In, respectively. The characteristics of energy bands and origin of minority band gaps were also studied. In addition, the effect of volumetric and tetragonal strain on HM character was studied. We also investigated the structural, electronic and magnetic properties of the doped Heusler alloys CoMnYGa1−xAlx, CoMnYAl1−xInxand CoMnYGa1−xInx(x = 0, 0.25, 0.5, 0.75, 1). The composition dependence of the lattice parameters obeys Vegard’s law. All alloy compositions exhibit HM ferromagnetic behavior with a high Curie temperature (TC).

International audience; In this paper, a performance analysis and economical/environmental assessment of two grid-connected PV systems in Meknes (Morocco) were carried out and their real energy production was reported. The PV system installed in an institutional building, consisted of polycrystalline silicon (Poly-Si) and monocrystalline silicon (Mono-Si) solar cell technologies. The monthly average and annual performance parameters of the PV systems assessed include the total energy generated, final yield, capacity factor and overall system efficiency. It is found that, for the same rated capacity, Poly-Si modules have higher monthly total average final yield than Mono-Si modules. Generally, the installed PV systems in Meknes possess higher performance indicators compared to other regions in the world like Greece, Ireland, India, South-Africa and UAE. This study has also evaluated the levelized cost of electricity (LCOE), Payback time (PB) and annual avoided CO2 emissions for the two systems under investigation. The LCOE found to be in the range 0.073\textendash0.082 \/kW h and PB found to be in the range 11.10\textendash12.69 years for this analysis. Furthermore, it was shown that the installed PV systems have the potential of reducing approximately 5.01 tons of CO2 emission per year.

As widely used sensors and actuators, piezoelectric materials have received great attention. Development of the smart structures can offer a great deal potential for use in advanced industry. This paper discuss the feasibility and efficiency of shape control of piezolaminated composite in antifouling process. The idea is to design an intelligent structural system that is able to protect itself against the fouling.

Introduction La depletion de la masse maigre constitue un facteur de mauvais pronostic chez les BPCO. Elle est constatee meme si l’IMC est normal. L’impedancemetrie est une methode simple est peut couteuse, elle est devenue de pratique courante dans l’evaluation de la composition corporelle. Nous avons utilise cette technique chez les patients BPCO dans un but d’evaluer leur etat nutritionnel. Methodes 60 patients BPCO (56 hommes et 4 femmes) âges entre 38 et 90 ans (moyenne 68, 73 ans), ont beneficie d’une evaluation de leur etat nutritionnel par deux methodes qui sont la mesure de l’indice de masse corporelle l’IMC et l’IMNG estime par impedancemetrie. Par la suite une comparaison a ete realisee entre les BPCO denutris et ceux de poids normal sur le plan fonctionnel, distance du test de marche de 6 min, le CAT, ainsi que le nombre d’exacerbations. Resultats Le VEMS etait Conclusion L’impedancemetrie corporelle est tres utile dans la detection des troubles nutritionnels chez les BPCO meme si leur poids est normal. Ce qui permet une prise en charge nutritionnelle precoce.

The effects of uncertainties on the nonlinear dynamics of complex structures remain poorly mastered and most methods deal with the linear case. This article deals with a model of a large and complex structure with uncertain parameters for the nonlinear dynamic case, and the reduction in the model discretized by the finite element method is obtained by reducing the degrees of freedom in the numerical model. This is achieved by the development of the unknown displacement vector on the basis of the eigenmodes; a particular attention is paid to the calculation of the nonlinear stiffness coefficients of the model. The method combines the stochastic finite element methods with a modal reduction class based on sub-structuring the component mode synthesis method. The reference method is the Monte Carlo simulation which consists in making several simulations for different values of the uncertain parameters. The simulation of complex and nonlinear structures is costly in terms of memory and computation time. To solve this problem, the perturbation method combined with the component mode synthesis reduction method significantly reduces the computational cost by preserving the physical content of the original structure. The numerical integration by the Newmark schema is used; the first statistical moments (mean and variance) of the nonlinear dynamic response are computed. Numerical simulations illustrate the accuracy and effectiveness of the proposed methodology.

Smart structures with integrated sensors, actuators, and control electronics are of importance to the next generation high-performance structural systems. In this study, thermopiezoelastic characteristics of piezoelectric beam continua are studied and applications of the theory to active structures in sensing and optimal control are discussed. Using linear thermopiezoelastic theory and Timoshenko assumptions, a generic thermopiezoelastic theory for piezolaminated composite beam is derived. Finite element equations for the thermopiezoelastic media are obtained by using the linear constitutive equations in Hamilton's principle together with the finite element approximations. The structure consists of a modeling of cantilevered piezolaminated Timoshenko beam with integrated thermopiezoelectric elements between two aluminium layers. The structure is modelled analytically and then numerically and the results of simulations are presented in order to visualize the states of their dynamics and the state of control. The optimal control LQG accompanied by the Kalman filter is applied. The effects of thermoelastic and pyroelectric couplings on the dynamics of the structure and on the control procedure are studied and discussed. We show that the control procedure cannot be perturbed by applying a thermal gradient and the control can be applied at any time during the period of vibration of the beam.

The reactions between monocrystalline GaAs(1 0 0) and thin polycrystalline Fe films have been investigated by application of conversion electron Mossbauer spectroscopy and high-resolution electron microscopy. The presence of a thin amorphous intermixed layer at the Fe/GaAs interface in as-deposited samples is first pointed out. The reacted layer, 8–10 nm thick, forms upon the native oxide of the GaAs substrate during the deposition process of the iron. The solid-state interdiffusions are also studied in the temperature range 400–550°C. They are shown to produce a layered microstructure of the type Fe/Fe 3 GaC y (0 ⩽ y ⩽ 0.5)/Fe x As ( x = 1, 2)/GaAs. The percentage of unmixed Fe atoms as well as the ferromagnetic and paramagnetic Fe fractions are calculated at each stage of an isochronal kinetic which also shows that the reactions are diffusion controlled with an activation energy of 1.5 eV. The orientation relationships at the Fe 2 As/GaAs and FeAs/GaAs interfaces, as well as the average grain size in the Fe 3 GaC y sublayer, are also determined.

The structural state at a Fe/GaAs interface has been investigated after ion-beam mixing (IBM) using X-ray diffraction, transmission electron microscopy and conversion electron Mossbauer spectroscopy. 50 and 100 nm thick Fe films were deposited on (100) GaAs substrates and the IBM was carried out at 293 K with 320 keV Kr 2+ ions to doses from 1 to 8 × 10 16 ions/cm 2 . The as-deposited films consisted of α-Fe and after mixing an amorphous Fe Ga As phase appeared in the subsurface zone. Different Fe coordination and magnetic states have been identified in the mixed layer and attributed to ferromagnetic Fe, paramagnetic Fe and paramagnetic Fe-oxide respectively, the former phase being the most abundant. The irradiation-dose growth led to a gradual decrease of α-Fe content and a monotone increase of amorphous phase content. For the 50 nm thick Fe films, complete mixing was obtained at a critical fluence of 5 × 10 16 ions/cm 2 . A study of mixing efficiency performed on 100 nm thick Fe films showed that the efficiency was somewhat less than 1, thus suggesting the onset of demixing processes.

The reaction between thin Fe films and gallium arsenide is studied using chiefly cross-sectional transmission electron microscopy. Fe films, 50–120 nm in thickness, were deposited onto (100) GaAs substrates by ion-beam sputtering and the Fe/GaAs couples were then annealed under vacuum at temperatures ranging between 400 and 550°C. The presence of a thin amorphous intermixed layer at the Fe/GaAs interface is pointed out in the as-deposited conditions; this layer consists of three elements Fe, Ga and As. The determination of the residual internal stress in the as-deposited Fe films is also performed using the sin2ψ method and the result is of the order of −2 GPa. Iron starts to react with GaAs at ⋍ 400 °C, producing a layered Fe/Fe3Ga/Fe2As + FeAs/GaAs structure. The sequence suggests that Fe diffuses into the GaAs and liberates Ga while forming iron arsenides. After annealing, the Fe/GaAs bimaterial also exhibits interfacial undulations which are discussed in terms of strain-energy relaxation.

The complete set of equations for describing the mechanical and electrical behavior of a piezoelectric medium is given. From these equations, the electromechanical equations describing the dynamical behavior of PVDFS and their mounting plate are derived. The electromechanical equations are used to explain antifouling process with the PVDFs as actuators. The transverse displacement is calculated using the electromechanical equations and compared with the experimental results. A comparison of the transverse displacement of the plate as a function of the applied PVDF voltage with the corresponding experimental case shows a good agreement. First, the optimal acceleration necessary for the antifouling marine prevention is found to be approximately 0.2 g by optical spectroscopy. Second, the activation energy and cycle of the PVDF actuators are determined.

Weed detection is a crucial issue in precision agriculture. In computer vision, variety of techniques are developed to detect, identify and locate weeds in different cultures. In this article, we present a real-time new weed detection method, through an embedded monocular vision. Our approach is based on the use of a cascade of discriminative classifiers formed by the Haar-like features. The quality of the results determines the validity of our approach, and opens the way to new horizons in weed detection. Full Text: PDF DOI: http://dx.doi.org/10.11591/ijece.v6i6.11878

For all marine experiments, a real problem concerns the protection of oceanographic sensors against fouling. It appears that one of the more efficient techniques to reduce marine fouling remains the surface generation of mechanical vibrations, even if the conditions of exposure are not optimal. Studies concerning prevention against marine fouling have proved the remarkable efficiency of transverse vibrations. In the considered spectral frequency ranges it appears that the excitation of high modes produces the best response for the modal amplitude. In the present work, we develop a two-dimensional theory to study the dynamic component of glass structures activated by piezoelectric actuators, perfectly bonded to the surface to be protected.

From the equations describing the mechanical and electrical behavior of a piezoelectric medium, the electromechanical equations describing the dynamical behavior of PVDFs and their mounting plate are derived. The electromechanical equations are used to explain the antifouling process with the PVDFs as actuators. The transverse displacement is calculated using the electromechanical equations and compared with the experimental results. A comparison of the transverse displacement of the plate as a function of the applied PVDF voltage with the corresponding experimental case shows good agreement. First, the optimal model acceleration necessary for the antifouling marine prevention is found to be approximately 0.2 g by optical spectroscopy. Second, the activation energy and cycle of the PVDF actuators are determined.

Conversion electron Mossbauer spectroscopy is used to investigate the ferromagnetic state of bcc stainless steel films. First, a low temperature study allows the resolution of the local Fe environments. It is found that the main environments correspond to three Fe sites with different short-range order. Second, a phase transition takes place at temperatures higher than 750 K. Evidence is found that, during an isothermal kinetic at 913 K, the ferromagnetic part of the Mossbauer spectra splits up into two components, thus indicating the existence of two ferromagnetic iron sites. The index n and activation energy Q in the Johnson-Mehl-Avrami plot are found to be 0.53-0.68 and 366–462 kJ mol −1 , respectively. The role of Cr atoms is also discussed.

In weed management, the distinction between monocots and dicots species is an important issue. Indeed, the yield is much higher with the application of a selective treatment instead of using a broadcast herbicide overall the parcel. This article presents a fast shape descriptor designed to distinguish between these two families of weeds. The efficiency of the descriptor is evaluated by analyzing data with the pattern recognition process known as the discriminant factor analysis (DFA). Excellent results have been obtained in the differentiation between these two weed species

A study is presented of magnetic and structural properties of thin Fe films deposited on (111) GaAs substrates for thicknesses ranging from 65 to 120 nm. The films grown by ion-beam-sputtering exhibit both bcc phase and ferromagnetic structure. Transmission electron microscopy has allowed to determine the morphological growth stages and the grain size of the films. Both vibrating sample magnetometry and Mossbauer effect measurements show that the magnetic moments are lying in the film plane for every film. The average magnetization and 57 Fe hyperfine field decrease with decreasing thickness which indicates the existence of two iron sites. An in-plane uniaxial anisotropy is found for the 65 nm thick film. Finally at film thickness approaching 120 nm, the film assumes the character of bulk α-Fe

We consider here a low-density assembly of colloidal particles immersed in a critical polymer mixture of two chemically incompatible polymers. We assume that, close to the critical point of the free mixture, the colloids prefer to be surrounded by one polymer (critical adsorption). As result, one is assisted to a reversible colloidal aggregation in the nonpreferred phase, due the existence of a long-range attractive Casimir force between particles. This aggregation is a phase transition driving the colloidal system from dilute to dense phases, as the usual gas-liquid transition. We are interested in a quantitative investigation of the phase diagram of the immersed colloids. We suppose that the positions of particles are disordered, and the disorder is quenched and follows a Gaussian distribution. To apprehend the problem, use is made of the standard phi(4) theory, where the field phi represents the composition fluctuation (order parameter), combined with the standard cumulant method. First, we derive the expression of the effective free energy of colloids and show that this is of Flory-Huggins type. Second, we find that the interaction parameter u between colloids is simply a linear combination of the isotherm compressibility and specific heat of the free mixture. Third, with the help of the derived effective free energy, we determine the complete shape of the phase diagram (binodal and spinodal) in the (Psi,u) plane, with Psi as the volume fraction of immersed colloids. The continuous "gas-liquid" transition occurs at some critical point K of coordinates (Psi(c) = 0.5,u(c) = 2). Finally, we emphasize that the present work is a natural extension of that, relative to simple liquid mixtures incorporating colloids.

Vibrational deformations of cylindrical elastic shell structures are controlled by piezopolymer transducers; the sensors could act both as actuators and receptors. Theoretical models and experimental results are presented. The mechanical models show the control of modal structural deformations. The equilibrium equations are obtained from the Hamilton principle, using the Love Kirchhoff hypothesis. Cylindrical structures were studied in view of vibration induced protection of ship hulls against marine fouling.

We present in this paper a new and general mathematical formulation on dynamic and vibration active control of elastic structures by piezoelectric materials.

This paper presents the active vibration control of rectangular thin plates by PVDF piezopolymer transducers. Theoretical and experimental results are presented.

The authors present a generalization of the S. Koshigoe and J.W. Murdock theoretical model. The considered structure vibrations are calculated and compared with experimental results. Complementary measurements of optical transmittance have been carried out by a spectroscopic study of glass plates immersed in a marine environment.

Early investigations on piezoelectric plates were based on a priori mechanical and experimental considerations. They assume plane stress and consider only transverse components of electric displacement and field. Beside, these were supposed constant in the plate thickness. Through an asymptotic analysis, this paper shows that mechanical hypotheses follow Kirchhoff-Love theory of thin plates. However, electric assumptions are found to be strongly dependent on the electric boundary conditions. That is, two regular problems should be distinguished: (1) the short circuited plate, for which only transverse electric displacement and field have to be considered-the electric potential is then found to be the sum of a known part, which depends on prescribed potentials, and an unknown part, which represents an induced potential and cannot be a priori neglected; the mechanical and electrical problems may be uncoupled; (2) the insulated plate, for which only in-plane electric displacement and field components are to be considered; the mechanical and electrical problems may be uncoupled for orthorhombic plates but not in general. Based on the above asymptotic analysis, two variational and local two-dimensional static models are presented for heterogeneous anisotropic plates. They are then applied to homogeneous and orthorhombic piezoelectric plates. For homogeneous orthorhombic piezoelectric plates, the electromechanical problem can be uncoupled. Hence, a mechanical problem is first solved for the mechanical displacement, then electric potentials are explicitly deduced from this displacement. Classical finite element codes having multilayer plate facilities can be used for solving the plate problems obtained.

We propose to adapt the asymptotic model of plate developed by Ciarlet to take into account specific effects as to the behavior of a piezoelectric device. Then we show how to distribute them in the thickness of a stratified composite structure, so as to detect or activate its strains optimal manner.